In addition to automatic transmissions having a planetary design, other automatic vehicle transmissions are known, e.g., so-called automatic shift transmissions or, for example, double clutch transmissions. These transmissions are usually operated with an electrically operated actuator which performs the gear shifting operations triggered by a corresponding transmission controller. If a vehicle equipped with such a transmission is parked and the driver leaves the vehicle, a parking lock of the transmission is usually activated to block an output shaft and thus prevent the vehicle from rolling away.
To this end, such transmissions often have a park by wire function which ensures that the parking lock is activated via a switch operated by means of the selective lever, for example. Such a system is disclosed in German Patent DE 102 59 893 A1, for example, which discloses a device for operating a parking lock of an automatically operated transmission having a mechanical spring mechanism which activates the parking lock automatically by interrupting the power supply to a holding actuator which holds the parking lock in a deactivated, i.e., unlocked, state and, after the power supply to the holding magnet is interrupted, the parking lock is automatically activated, i.e., falls into the locked position. To this end, the interruption in power supply must be induced by the transmission controller so that, after a failure of the control pulse, triggering the transmission control accordingly, it may happen that the transmission controller does not interrupt the power supply to the holding magnet and thus the parking lock does not automatically engage.
Against this background, there is a long felt need for a device for operating a parking lock of a transmission, especially an automatic transmission, which will avoid these disadvantages.